In the nicely written article https://arxiv.org/abs/1803.06917 by Justin Sirignano and Rama Cont, they explained that their model is universal and stationary. I am a bit confused about some questions.
- What makes that model any different from other models?
- What do they called the "Universal Features"?
- As they use petabyte of data, i.e. 1000 stocks over on 3 years, can we achieve the same results with 3 stocks over 3 years instead?